REG - First Dev. Resources - Selta Project – Exploration Update

First Development ResourcesAnnouncement

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RNS Number : 5569T  First Development Resources PLC  19 February 2026

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19 February 2026

First Development Resources plc

('First Development", "FDR" or the "Company')

Selta Project - Exploration Update

Rare-Earth Element Stream Sediment Sampling Results and Target Refinement

First Development Resources plc (AIM: FDR), the UK-based, Australia-focused
exploration company with mineral interests in Western Australia and the
Northern Territory, is pleased to provide results and interpretation from the
December 2025 stream sediment sampling programme completed at its Selta
Project ("Selta" or the "Project") located in the Aileron Province of
Australia's Northern Territory.

The programme was undertaken across the West Nintabrinna and Ingallan
rare-earth element ("REE") target areas and was designed as a low-cost,
first-pass exercise to refine previously identified anomalism and define
priority areas for focused follow-up exploration.

HIGHLIGHTS

·    Highest assay of 2,103 ppm total rare-earth elements + yttrium
("TREE+Y") returned at West Nintabrinna, with coherent multi-sample anomalism
confirming a fertile intrusive system. Encouraging TREE+Y results (up to 385
ppm) also returned from Ingallan.

·    Target areas significantly refined: West Nintabrinna from c.75km² to
c.5km² ("Tourmaline") and Ingallan reduced from approximately 90km² to
c.8.5km² ("Peake Bore"), materially improving targeting precision.

·    Geochemical signatures indicate localised granite fractionation and
enrichment consistent with potential pegmatite-hosted lithium (Li) and REE
mineralisation.

·    Discrete intrusive features at West Nintabrinna and distinct 1.8km
strike pale outcrop identified at Ingallan define clear follow-up mapping and
drill-target pathways.

·    Gradient Array Induced Polarisation ("GAIP") survey at Lander West
gold target c.50% complete. Survey temporarily paused due to inclement weather
conditions affecting access.

 

Tristan Pottas, Chief Executive Officer of FDR, commented:

"The December stream sediment programme has delivered a strong outcome and
materially advanced our understanding of the REE potential at Selta.

Importantly, we have reduced broad conceptual targets to clearly defined
priority zones at both West Nintabrinna and Ingallan. The 2,103 ppm TREE+Y
result at West Nintabrinna is particularly encouraging and supports our
interpretation of a fertile intrusive system capable of hosting rare-earth
mineralisation.

This low-cost programme has significantly improved our targeting efficiency
and provides a clear and systematic pathway for the next phase of REE
exploration at Selta."

DECEMBER 2025 STREAM SEDIMENT SAMPLING PROGRAMME

The field programme, completed over one week in December 2025, comprised
systematic stream sediment sampling and reconnaissance geological observations
across the two priority Li and REE target areas (Figure 1) previously
identified from historical data review and announced 19 November 2025:

Selta Project - REE Exploration Update - 07:00:04 19 Nov 2025 - FDR News
article | London Stock Exchange
(https://www.londonstockexchange.com/news-article/FDR/selta-project-ree-exploration-update/17333530)

Stream sediment sampling provides an effective regional screening tool by
characterising upstream catchment geology and metalliferous signatures. The
primary objectives of the programme were to:

•     Validate historical geochemical anomalies;

•     Increase sampling density;

•     Identify discrete anomalous catchments;

•     Refine target areas for follow-up exploration.

Samples were analysed using ALS Globals Lithium borate fusion (ME-MS81)
method, this method was selected to maximise the recovery of resistive heavy
minerals commonly associated with REE and lithium-caesium-tantalum ("LCT")
style pegmatite systems. With statistical analysis applied to identify
fractionated trends within the collected samples, to allow for the systematic
evaluation of the West Nintabrinna and Ingallan target areas.

Figure 1: Location of stream sediment samples from sample locations within the
West Nintabrinna and Ingallan target areas.

 

WEST NINTABRINNA STREAM SEDIMENT RESULTS

West Nintabrinna delivered the strongest geochemical results of the programme,
with TREE+Y values of up to 2,103 ppm (Figures 2 and 3), representing the
highest results recorded in this phase of exploration. In total 21 samples
were collected.

Three strongly anomalous samples define a coherent central catchment now
referred to as the "Tourmaline target area", draining the core of the outcrop.
Geochemical patterns indicate an evolved felsic intrusive signature consistent
with fertile magmatic systems capable of hosting REE-bearing pegmatites.

Airborne imagery highlights multiple discrete pale-weathering outcrops within
the anomalous zone, which may correspond to small intrusive or pegmatitic
bodies contributing to the observed enrichment.

The programme has reduced the effective West Nintabrinna exploration footprint
from approximately 75km² to approximately 5km², materially improving
targeting precision and cost efficiency for follow-up work.

Figure 2: Extent of the Tourmaline target area and enriched streams on the
West Nintabrinna target area.

Figure 3: Image of the sample location WN011, which recorded up to 2,103 ppm
TREE+Y values.

 

INGALLAN STREAM SEDIMENT RESULTS

Results from the 20 stream sediment samples collected at the Ingallan Target
Area show that REE enrichment is localised rather than evenly distributed
across the mapped granite and metasedimentary rocks.

TREE+Y values of up to 385 ppm were returned within a central zone now defined
as the "Peake Bore Target" (Figure 4). Geochemical patterns indicate:

•     Localised granite fractionation;

•     Enrichment in incompatible elements;

•     Heavy mineral assemblages consistent with evolved intrusive
phases.

Drainage basin analysis has reduced the effective exploration footprint from
approximately 90km² to around 8.5 km², focusing exploration on the Peake
Bore target as a high-priority area for potential LCT- and REE-bearing
pegmatite mineralisation.

Within the Peake Bore target, a north-northeast-trending pale-weathering
outcrop of approximately 1.8 km strike and 10 to 30 metre width has been
identified from airborne imagery and field observations. A further c.1 km
east-west-trending pale outcrop, along with additional pale-weathering
exposures associated with elevated geochemistry, has also been recognised.
These features represent key hard-rock targets for follow-up mapping and
rock-chip sampling.

Although the area remains largely untested, its proximity to two large
granitic intrusions provides a favourable geological setting for the formation
of pegmatite-hosted REE mineralisation. The current programme did not evaluate
ionic clay REE potential in the western part of Ingallan, which remains
untested.

Figure 4: Extent of the Peake Bore Target area, enriched streams and target
outcrops on the Ingallan target area.

 

GEOLOGICAL CONTEXT

The Selta Project lies within the Aileron Province of the Arunta Region in
Australia's Northern Territory, a Proterozoic terrane known for hosting
evolved granitic systems associated with tin (Sn), tungsten (W), uranium (U)
and rare-metal mineralisation.

Rare-earth elements, commonly reported together with yttrium as TREE+Y due to
its similar chemical behaviour and occurrence in the same mineral systems, are
typically enriched during the late stages of granite crystallisation. Where
this fractionation becomes localised, it can form discrete intrusive or
pegmatitic bodies capable of hosting concentrated REE mineralisation.

The stream sediment results at both West Nintabrinna and Ingallan show
geochemical signatures consistent with this type of evolved, fractionated
system. Importantly, the anomalism is spatially restricted rather than broadly
dispersed, suggesting defined source areas rather than background enrichment.

In this regional geological setting, the presence of localised REE enrichment,
elevated incompatible element signatures and coherent anomalous catchments is
considered encouraging and supports further targeted exploration.

NEXT STEPS

The results of the December programme have refined and prioritised exploration
targets at Selta.

The Company intends to:

•     Undertake detailed geological mapping across Peake Bore and the
Tourmaline refined target areas;

•     Conduct systematic rock-chip sampling of identified outcrops;

•     Complete additional targeted geochemical work where appropriate;

•     Evaluate high-resolution geophysics to assist in drill target
definition;

•     Progress toward potential drilling, subject to results.

REE exploration remains central to the Company's strategy at Selta, alongside
the ongoing geophysical work on the Lander West gold target area.

GAIP SURVEY UPDATE

The GAIP survey at the Lander West gold target commenced in early January 2026
and is designed to complement the previously completed high-resolution
aeromagnetic and radiometric surveys. The programme aims to enhance the
Company's understanding of subsurface geology and structural architecture
across the target area, supporting the refinement of potential drill targets.

Adverse weather conditions currently affecting Central Australia have resulted
in a temporary pause to field operations. The survey is approximately 50%
complete will resume once conditions permit.

Chief Executive Officer Tristan Pottas is expected to visit site in early
March, and the Company will provide a further update in due course.

 

Qualified Person Statement

The technical information contained in this disclosure has been reviewed and
approved by Mr Nicholas O'Reilly (MSc, DIC, MIMMM QMR, MAusIMM, FGS), who is a
qualified geologist and acts as the Qualified Person under the AIM Rules -
Note for Mining and Oil & Gas Companies. Mr O'Reilly is a principal
consultant working for Mining Analyst Consulting Ltd which has been retained
by First Development Resources plc to provide technical support.

GLOSSARY

 Term                              Definition
 Fertile intrusive system          An igneous intrusion whose chemistry indicates it has evolved sufficiently
                                   during crystallisation to concentrate rare or economically important elements.
 Geochemical signature             The characteristic pattern and relative abundance of elements within a rock or
                                   sediment sample that reflects its source geology and mineral potential.
 Granite fractionation             The progressive chemical evolution of a granite magma during cooling, which
                                   can concentrate rare and incompatible elements into late-stage phases.
 Incompatible elements             Elements that preferentially remain in the molten portion of a magma during
                                   crystallisation, leading to enrichment in late-stage intrusive phases.
 LCT style pegmatite               A lithium-caesium-tantalum enriched pegmatite formed from highly evolved
                                   granitic melts and commonly associated with rare-metal mineralisation.
 Pegmatite                         A very coarse-grained igneous rock, typically formed during the final stages
                                   of magma crystallisation, which can host concentrated rare metals and
                                   minerals.
 Rare-earth element                A group of 17 metallic elements, including the lanthanides plus yttrium and
                                   scandium, commonly used in high-technology and critical energy applications.
 REE bearing pegmatite             A pegmatite containing minerals enriched in rare-earth elements, typically
                                   formed from highly fractionated granitic systems.
 Stream sediment sampling          An exploration technique that analyses sediments collected from drainage
                                   channels to detect geochemical signals from upstream bedrock.
 Total rare-earth elements (TREE)  The combined concentration of all rare-earth elements in a sample, typically
                                   expressed in parts per million (ppm) or as a percentage of rare-earth oxides,
                                   used to indicate the overall level of rare-earth enrichment.
 Yttrium (Y)                       A critical metal that behaves chemically like the heavy rare-earth elements
                                   and is commonly reported alongside them (TREE+Y) because it occurs in the same
                                   minerals and geological systems.

 

For further information visit www.firstdevelopmentresources.com
(http://www.firstdevelopmentresources.com) or contact the following:

 First Development Resources plc  Tel: +44 (0) 20 3778 1397

 Tristan Pottas (CEO)
 Beaumont Cornish Limited         Tel: +44 (0) 20 7628 3396

 Nominated Adviser

 Roland Cornish / Asia Szusciak
 SI Capital Limited               Tel: +44 (0) 1483 413 500

 Broker

 Nick Emerson

Beaumont Cornish Limited ("Beaumont Cornish") is the Company's Nominated
Adviser and is authorised and regulated by the FCA. Beaumont Cornish's
responsibilities as the Company's Nominated Adviser, including a
responsibility to advise and guide the Company on its responsibilities under
the AIM Rules for Companies and AIM Rules for Nominated Advisers, are owed
solely to the London Stock Exchange. Beaumont Cornish is not acting for and
will not be responsible to any other persons for providing protections
afforded to customers of Beaumont Cornish nor for advising them in relation to
the proposed arrangements described in this announcement or any matter
referred to in it.

ABOUT FIRST DEVELOPMENT RESOURCES

First Development Resources' assets comprise eight granted tenements covering
a total area of 2,314.4km(2). Five of the tenements, comprising three
prospective copper-gold projects, are located in Western Australia (WA) while
the remaining three tenements, comprising a rare-earth element (REE), uranium,
lithium and gold project, are located in the Australian's Northern Territory.
All tenements are wholly owned by FDR. The assets are a mixture of drill ready
and earlier stage exploration.

The WA Projects include the Company's Wallal Project as well as Ripon Hills
and Braeside West Projects situated in the Paterson Province, which is widely
regarded as one of the most productive regions in Australia for the discovery
of world-class gold-copper deposits, and which is home to several world-class
mines and more recent discoveries.

The Selta Project in the Northern Territory is located in an area considered
highly prospective for uranium and rare-earth element mineralisation along
with base and precious metal mineralisation. Numerous companies are actively
exploring within the region.

Beyond the existing portfolio, FDR is actively looking to expand its portfolio
through the acquisition of early-stage exploration projects in Australia.

 

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